In recent years, an image display device in which an organic light emitting diode (OLED: organic light emitting diode) is formed on a resin film substrate having flexibility has been put to practical use. When a flexible electronic device such as an image display device is formed on such a flexible resin film substrate, it is necessary to hold the resin film substrate flat. Therefore, generally, a thermosetting resin such as a polyimide precursor is coated on a flat glass substrate and further cured at a certain temperature to form a resin film substrate such as polyimide held on the glass substrate. Then, subsequent to forming a circuit element for driving the organic light emitting diode on the resin film substrate held on the glass substrate, it is carried into a vapor deposition apparatus to form an organic light emitting diode structure such as reflective electrodes (anodes), a hole injection layer, a hole transport layer, light emitting layers, an electron transport layer, an electron injection layer, and extremely thin metal electrodes (cathodes) having translucency by vapor deposition. Then, after forming an electronic device structure comprising a driving circuit and the organic light emitting diode structure on the resin film substrate, second laser beams having a shorter wavelength such as ultraviolet rays are irradiated to metamorphose the interface between the glass substrate and the resin film from the back side of the glass substrate, that is, from the side where the resin film substrate is not formed, for making it easy to separate the resin film substrate from the glass substrate. Furthermore, first laser beams having a longer wavelength such as infrared rays are irradiated to circumferences of an area where the electronic device structure is formed from the front side of the glass substrate so as to separate off the flexible electronic device formed on the resin film substrate therefrom. In the case of manufacturing a lot of the flexible electronic devices from a single resin film substrate, vapor deposition materials are deposited so that individual flexible electronic devices are arranged in a matrix shape. Then, when the flexible electronic devices are formed, the first laser beams are linearly scanned along the arrangement direction of each side of the electronic devices to separate the individual flexible electronic devices from the resin film substrate.
As will be described later, since the order of irradiation of the first laser beams and the second laser beams is different from those of the method of manufacturing flexible electronic devices according to the present invention, the laser beams which appear first are referred to as “second laser beams” and the laser beams which appear afterwards are referred to as “first laser beams”. The term “electronic device structure” means a structure serving as an electronic device such as a circuit element for driving an organic light emitting diode formed on a resin film substrate and the organic light emitting diode structure which comprises reflective electrodes (anodes) formed on the circuit element, a hole injection layer, a hole transport layer, light emitting layers, an electron transport layer, an electron injecting layer, and metal electrodes (cathodes), and the term “flexible electronic device” means a completed electronic element including the electronic device structure and the resin film substrate surrounding the same (the same applies hereafter).
By the way, in the conventional method for manufacturing flexible electronic devices, since the first laser beams are irradiated over the entire surface of the resin film substrate formed on the glass substrate, the resin film substrate in areas not used for the flexible electronic devices are peeled from the glass substrate, too. Therefore, when the flexible electronic devices together with the glass substrate are conveyed to the next process to connect driver ICs or the like to the manufactured flexible electronic devices, the glass substrate must be carefully handled so as not to drop the flexible electronic devices from the glass substrate. Therefore, according to the manufacturing method of flexible electronic devices described in Patent Literature 1, peeling prevention layers are formed in rectangular frame shapes at circumferences of device formation areas where flexible electronic devices are formed so as to suppress amounts of transmission of first laser beams for peeling the resin film substrate, so that only interfaces of the glass substrate and the resin film substrate in the device formation areas are metamorphosed. Consequently, even when the flexible electronic devices together with the glass substrate are conveyed to the next process, since the resin film substrate at the portions where the peeling prevention layers are formed adheres to the glass substrate and serves as guides, the flexible electronic devices hardly drop from the glass substrate.
In the method for manufacturing flexible electronic devices described in Patent Literature 1, a process for forming the peeling prevention layers at the circumferences of the device formation areas is required, and in the case of reusing the glass substrate, a process for removing the peeling prevention layers from the glass substrate is further required. Consequently, they cause the increase of the manufacturing cost of the flexible electronic device. In addition, in the case of manufacturing a lot of the flexible electronic devices from a single resin film substrate, in order to decrease the manufacturing cost by increasing the utilization efficiency of the members, clearances between individual flexible electronic devices (or device formation areas) tend to be narrower, so that it is impossible to connect flexible printed boards on which driver ICs or the like are disposed to the flexible electronic devices held on the glass substrate, and thus, it is necessary to attach the flexible printed board to the flexible electronic device after removing it from the glass substrate. At that time, since four corners of the individual flexible electronic device are sharpened, the flexible electronic devices may be damaged by the sharp corners when the flexible electronic devices removed from the glass substrate come into contact with each other. Furthermore, since a resin film substrate such as a polyimide film tends to warp due to the influence of water absorbing or the like when it left, if the four corners of the flexible electronic device are sharpened, the corner may be bent when it comes into contact with something.